Computer printers commonly employ single or multiple print heads positioned on a reciprocating print head carriage. A printer ribbon cartridge used in computer printers includes one or more ribbon guides--a device which guides the print ribbon over a printing surface of a print head--which attach to the print heads.
A conventional three ribbon guide arrangement for a three-head printer is shown in FIG. 1. The ribbon guides 22a, 22b, and 22c are mounted on a conventional printer ribbon cartridge 10 having a cartridge housing 12 which houses and protects a continuous print ribbon 14. The cartridge housing 12 includes a housing body 16 and two guide arms 18 and 20. The housing body 16 stores the bulk of the continuous print ribbon 14. The two guide arms 18 and 20 extend substantially perpendicular from the housing body 16 to support and guide the print ribbon 14 from the housing body 16. An exposed print section of the print ribbon 14 extends between the two guide arms 18 and 20. The three ribbon guides 22a, 22b, and 22c are slidably coupled to the exposed print section of the print ribbon 14. The ribbon guides 22a, 22b, and 22c attach to complementary guide supports on respective print heads of the printer (not shown) to guide the print ribbon 14 over the print heads.
One conventional ribbon guide assembly having the ribbon guide 22a and a print head 24 is shown in FIG. 2. The ribbon guide 22a has a rear section 25 and a central section 28. The rear section 25 and the central section 28 are open at the bottom of the ribbon guide 22a as illustrated generally by reference numeral 27. The rear section 25 has two rectangular grooves 26 formed in each side. The central section 28 also has two rectangular grooves 30 formed in each side.
The ribbon guide has a front section that includes upper ribbon guide elements 32 (only one element is shown in this perspective view) and lower ribbon guide elements 36a and 36b. The upper ribbon guide elements 32 is formed adjacent the central section 28 and extends downward over the print ribbon 14. The lower ribbon guide elements 36a and 36b are supported by a pair of triangular flanges 38 (only the near side is shown) formed along the bottom of the central section 28 and extend upward over the print ribbon 14. The depicted triangular lip 38 extends outward at an angle from a position flush with an edge 29 of the central section 28. The upper ribbon guide elements 32 and the lower ribbon guide elements 36a and 36b define a path for the print ribbon 14.
The print head 24 has a nose section 40 with guide supports in the form of first rectangular flange 42 and second rectangular flange 44. The nose section 40 contains plural pin wires and pin wire guides (not shown). The pin wires are directed through the nose section 40 on the pin wire guides to a linear array at the front 46 of the print head 24. The first flange 42 has a width which is slightly less than the width of the grooves 26 of the rear section 25 of the ribbon guide 22a. The second flange 44 has a width which is slightly less than the width of the grooves 30 of the central section 28. As a result, the ribbon guide 22a may be mounted on to the print head 24 by aligning the support grooves 26 and 30 with the first and second flanges 42 and 44, respectively, and then sliding the ribbon guide 22a onto the print head 24. Once mounted, the ribbon guide 22a guides the print ribbon 14 over the linearly arrayed pin wires at the front 46 of the print head 24.
One of the problems associated with the above described ribbon guide assembly is that the ribbon guide is mounted on the nose section of the print head which can provide additional stresses on the print head, not only during installation of the ribbon guide, but also during operation. Additionally, it is more difficult to mount securely the ribbon guide on the guide supports.
One of the objects and advantages of the present invention is the provision of a ribbon guide assembly that does not provide additional stresses on the print heads and is easier to assemble and disassemble.